Merge pull request #8617 from markdroth/service_config_json

BUILD

CMakeLists.txt

Makefile

binding.gyp

build.yaml

config.m4

gRPC-Core.podspec

grpc.gemspec

include/grpc++/channel.h

include/grpc++/support/channel_arguments.h

include/grpc/impl/codegen/grpc_types.h

package.xml

src/core/ext/client_channel/client_channel.c

src/core/ext/client_channel/lb_policy_registry.c

src/core/lib/channel/message_size_filter.c

src/core/lib/json/json.c

src/core/lib/json/json.h

src/core/lib/support/string.c

src/core/lib/support/string.h

src/core/lib/transport/mdstr_hash_table.c